The instant invention pertains to the art of variable voltage AC power supply having an input at which an AC voltage is applied and an output at which a voltage of variable magnitude can be used to power an appliance. The type of variable voltage power supply with which the invention deals applies particularly to devices used for dimming incandescent lights in a plant or residence.
Various types of devices for dimming lights are known to the art including variable transformers, rheostats and those employing high-speed switching devices such as silicon-controlled rectifiers and triacs.
In prior art devices employing high-speed switching devices to disconnect the line voltage from the appliance during portions of the alternating voltage cycle, a control must normally be turned or otherwise moved to a position consistent with the turn-on point of the switching device in the AC cycle. Although useful for some applications, these devices have shortcomings which render them difficult to use in others. For example, if the level of light is to be controlled from a remote location, radio controlled servo-motors must be used to position the control. Prior art devices also do not lend themselves to use with touch-actuated controls which can provide a constant voltage signal during the duration of a pressure, temperature or body capacitance applied to the surface of the controls. Such controls, in addition to their utility, are aesthetically pleasing particularly when used in modern decors.